1. Field of the Invention
The present invention relates to an image forming apparatus, a line width control method and a line width control program product embodied in a computer readable medium. In particular, the present invention relates to an image forming apparatus, a line width control method and a line width control program product embodied in a computer readable medium each capable of reproducing a fine line of high quality.
2. Description of the Related Art
In a case that an image input apparatus such as a facsimile moves an original draft to read an image thereof, even when fine lines having a single width are read, those in a main scanning direction (lateral fine lines) are higher in output than those in a sub-scanning direction (vertical fine lines). Therefore, the fine lines in the sub-scanning direction are not corrected so much as compared with the fine lines in the main scanning direction. As a result, the lateral fine lines corresponding to the sub-scanning direction are degraded in image quality, for example, the lateral fine lines are patchy.
In order to overcome this problem, Japanese Laid-Open Patent Publication No. 06-030267 (hereinafter, referred to as Patent Document 1) proposes an image reading apparatus capable of preventing patchy lateral fine lines and achieving improved image quality. According to this image reading apparatus, in a case that a lateral fine line minimum output is higher than a vertical fine line minimum output with regard to minimum output characteristics for a line width in an image input unit, a weight coefficient for a pixel in a sub-scanning direction is made larger than a weight coefficient for a pixel in a main scanning direction by an MFT correction in an image processing unit. Thus, a lateral fine line is prevented from being patchy upon read of an image.
However, even in image data inputted as described above, when a font is printed by an image forming apparatus such as an MP (Multi Function Peripheral), a dot tends to be expanded depending on performance of an engine. As a result, there arises a problem that reproducibility of a fine line is degraded.
When reproducibility of a fine line is degraded, the fine line can not be reproduced, so that there arises a problem that a type of a font can not be identified. In addition, the fine line is not outputted as a fine line, so that there arises a problem that an outputted image is degraded in quality. There also arises a problem that a font having a small size can not be identified.